Soil treating apparatus



March 12, 1968 w. L. AMMANN SOIL TREATING APPARATUS 4 Sheets-She et 1Filed July 21, 1966 INVENTOR. WILLIAM L. AMMANN ATTORNEY March 12, 1968w. AMMANN 3,372,658

SOIL TREATING APPARATUS Filed July 21, 1966 4 Sheets-Sheet 2 75 no I7476 I36 I50 I56 I52 98 FIG. 4-

INVENTOR. WILLIAM L. AMMANN B WaflW/ ATTORNEY W. L. AMMANN SOIL TREATINGAPPARATUS March 12, 1968 Filed July 21, 1966 4 Sheets-Sheet 5 FIG. 5

INVENTOR. WILUAM L. AMMANN Mam ATTORNEY W. L. AMMANN SOIL TREATINGAPPARATUS March 12, 1968 4 Sheets-Sheei 4 Filed July 21, 1966 INVENTOR.WILLIAM L. AMMANN BY MAW ATTORNEY Office 3,372,658 Patented Mar. 12,1968 ABSTRACT OF THE DISCLOSURE Apparatus for and a method of subsurfaceinjection of anhydrous ammonia fertilizer wherein liquid is conductedfrom a source of liquid ammonia traversed over a field to a subsurfaceinjection unit from which the ammonia is discharged, with the ammoniabeing maintained under a sufficient pressure throughout substantiallyits entire travel to the injector unit to hold the same substantiallyentirely in its liquid state during such travel. The apparatus includesa plurality of spaced injector units connected by individual conduits toa manifold, such manifold having communication with the liquid contentsof a supply vessel by way of a single conduit provided with a pressureregulator, filter and shut-off valve. Each of the individual conduits isprovided immediately adjacent its respective injector unit with acontrol valve which is normally closed, the arrangement being such thatammonia is supplied to the individual control valves as a liquid under aregulated pressure that is sufficient to maintain the same in a liquidstate. Each of the control valves is provided with fluid pressureactuated means for opening such valves, and all of such means areconnected by a common conduit to a master control valve, and the latteris such that the common conduit can be selectively vented and placed incommunication with a source of fluid pressure, which can be the vaporspace at the top of the ammonia storage vessel.

The present invention relates to new and useful improvements inagricultural apparatus for subsurface injection of soil treating fluids,and more particularly pertains to apparatus for injecting treatingfluids that include a volatile substance (such as ammonia, butane, etc.)carried in the liquid state by the apparatus.

At the present time, soil fertilization or treatment is being conductedon a major scale by the subsurface injection of anhydrous ammonia.Apparatus used for this purpose conventionally includes a vehicle fortraversing the field, a pressure vessel on the vehicle for containinganhydrous ammonia in the liquid state and from which ammonia isconducted by a plurality of conduits to an equal number of groundpenetrating injector units that discharge the ammonia as the vehicletravels along. An injector unit is usually in the form of a bladeadapted to project below the surface of the ground and to cut throughthe ground as the vehicle advances (with perhaps an assist insofar ascutting is concerned by such blade being arranged to trail a groundpenetrating colter wheel), such blade incorporating or having attachedthereto an end portion of the ammonia conduit, and the latter having adischarge opening at a position to discharge ammonia beneath the groundsurface when the blade is in ground penetrating position. Conventionalapparatus may optionally also include means such as a roller or chaintrailing each injector unit to fill or close, at least to some extent,such cut or furrow that may remain open after the passage of the bladeof the injector.

Exemplary of prior art proposals as to apparatus such as discussedbriefly above (some of which have to some extent had features thereofcarried into actual practice) may be mentioned the disclosures of thefollowing listed US. patents:

2,888,891, Liquid Fertilizer Attachment, June 2, 1959,

Ackley 2,973,728, Anhydrous Ammonia Metering Dispenser,

Mar. 7, 1961, Garretson 2,781,733, Apparatus for Dispensing MaterialBeneath the Shank of a Ground-Working Tool, Feb. 19, 1957, Graham2,415,251, Soil Treating Process, Feb. 4, 1947, Leavitt 2,691,358,Fertilizer Flow Controller, Oct. 12, 1954,

Peck

2,782,739, Distribution of Fluids, Feb. 26, 1957, Freer 3,139,848, FluidDistribution, July 7, 1964, Welty 2,637,979, Dispensing Tank and ValveStructure, May 12,

1953, Pool et al.

3,148,642, Soil Treating Apparatus, Sept. 15, 1964, Gould 3,012,526,Method of Injecting Liquids Into the Soil, Dec.

12, 1961, Baldwin et a1.

2,912,944, Nov. 17, 1959, Snow et al.

The above listed US. patents set forth quite clearly the objects andadvantages of such systems for soil treatment, and also disclose quitewell the general principles of structure and function of such apparatus.Since the objects, advantages and principles of structure and functionof apparatus (and processes performed in the use of such apparatus) suchas disclosed in the above patents are well known to those skilled in theart, there is no need to repeat or discuss such disclosures hereininsofar as those familiar with the art are concerned, it beingunderstood that such disclosures are incorporated herein by referencewith it being left to those less' familiar with the art to consultsuchof the above listed and generally available patents as may be necessaryfor edification about the subject.

The present trend of the art is to include with ammonia other treatingagents such as sulphur, and in such instances the ammonia not onlyserves as a fertilizer that is injected with a pressure developed fromits own volatility or vapor pressure, but additionally serves what mightbe termed the functions of carrier and propellant for other treatingagents that might be dissolved, emulsified or dispersed as a suspensionin the liquid ammonia. Ap'partaus of the same general character can beemployed for in jecting volatile substances other than ammonia, suchother volatile substances being an active soil treating agent and/ or acarrier and propellant. For example, such other volatile substance canbe liquified petroleum gas (propane and/ or butane, and the like).

Whatever the character of the liquified volatile substance andregardless of whether such substance is in admixture with othermaterials, prior art devices and proposals for injection such substanceas a vapor in the ground are subject to certain shortcomings. Among manysuch shortcomings may be mentioned such as vaporization occurring insuch a manner or at such a position as to cause an intolerableaccumulation of frozen earth on the injector by reason of therefrigeration effect of the vaporization; deposit of residues (such assulphur) from an ammonia carrier such as to obstruct and greatlyattenuate subsequent fiow of ammonia; a lack of uniformity of rates ofinjection as between various injectors; and agreat waste of ammonia onattempting to make a turnaround at the end of the field being treated byreason of valving being at a position in the distribution conduitsremote from the injectors and the consequent loss of fluids in theportions of the conduits intermediate the valves and the injectors.

It is a primary object of the present invention to provide apparatusthat will overcome or greatly minimize each and every one of thedifliculties mentioned in the preceding paragraph.

Another important object of the present invention is to produceapparatusof the character specified above such that will enable adjustment of therates of insertion of treating fluids for each of the individualinjectors, whereby variations in concentration of treating agents may beobtained, and uniformly between the various injectors also obtained.

Yet another object of the present invention is to provide apparatus ofthe character specified above which will be simple and reliable inoperation, and which will also be economical in manufacture as well asdurable in use.

Still another object of the invention is to provide individual valvesfor each of the injectors, such valves being positioned in the immediateproximity of such injectors, together with means for actuating suchvalves in unison from a remote position.

An extremely important aspect of the invention involves, in the methodof soil treatment, wherein a treating unit is caused to traverse afield, such treating unit including a vessel for containing liquidanhydrous ammonia and a soil penetrating injector with a conduitconnecting the vessel and the injector, and wherein ammonia is passedfrom the vessel into the conduit, passed through the latter and thencethrough the injector and is discharged from the injector beneath thesurface of the soil; the improvement in such method comprisingintroducing the ammonia into the conduit from the vessel in its liquidstate, and thereafter maintaining the ammonia under a pressure along itspassage suflicient to prevent vaporization of more than a minor fractionthereof prior to discharge thereof from the injector, whereby most ofthe ammonia vaporizes subsequent to its discharge from the injector.

Another important aspect of the invention involves, in agriculturalapparatus of the type including a plurality of ground penetratinginjectors for subsurface injection of soil treating fluids, suchinjectors being connected by individual conduits to a common source ofsupply of soil treating fluids, with valve means being provided to shutoff fluid communication between the injectors and the source of supplythrough said conduits; the improvement wherein said valve meanscomprises an individual shutoff valve in each of the individual conduitswith each of such valves being disposed in its respective conduit at aposition therealong substantially spaced from the common source andmeans including a single control for actuating all said valves inunison, whereby all fluid communication between the injectors and thesource as well as the portions of the conduits between the source andthe valves can be shut off.

' Still another important aspect of the invention has to do with apressure controlled valve comprising a valve body having a generallyL-shaped fluid passageway therethrough that is partially defined by anannular valve seat, said body being provided with a cylindrical bore inaxial alignment with the valve seat and having an inner end spaced fromthe passageway, said body having a cylindrical opening therein in axialalignment with the bore and the valve seat and extending from the innerend of the bore to the passageway, a piston slidable in the bore todefine a sealed chamber in the bore intermediate the inner end of thelatter and the piston, a valve stem fixed to the piston to projecttoward the valve seat, said valve stem slidably and sealiugly extendingthrough said opening, said valve stem being provided with a valvingelement at its end remote from the piston,

said valving element being sealiugly engageable with the valve seat toclose the passageway on movement of the piston toward the inner end ofthe bore, said valving element including a tapered portion projectinginto the valve seat, said valving element and the valve seat being soconstructed and arranged that the passageway is progressively opened asthe valving element is moved from sealing engagement with the valve seaton movement of the piston from the inner end of the bore, a controlfluid passageway in the valve body communicating with the chamberwhereby a fluid pressure can be applied to move the piston from theinner end of the bore, a plate mounted on the body at the outer end ofthe bore, a compression spring in the bore biased between the plate andthe piston for yieldingly urging the piston toward the iner end of thebore, said plate having a threaded opening therethrough, and a stopmember threadingly extending through the threaded opening and into thetravel path of the piston, whereby a fine adjustment can be made as tothe limit of movement of the piston from the inner end of the bore andequally fine adjustment obtained as to the maximum opening of theL-shaped passageway.

Yet another important aspect of the invention involves, for use in afluid pressure controlled system of the type including conduit means forcontrolled fluid pressure, the improvement comprising first and secondshutoff valves each operatively connected to said conduit means forcontinuous fluid communication therewith, said first valve beingconnected to a source of pressurized fluid whereby opening of the firstvalve admits fluid under pressure to the conduit means, said secondvalve being in communication with ambient atmosphere whereby opening ofthe second valve vents the conduit means to atmosphere, meansoperatively interconnecting said and second valves for alternate closureof said first and second valves, said first and second valves eachincluding an actuating valve stem with said valve stems being parallelto each other and having free ends, said means for alternate closure ofsaid valves comprising a pair of cam wheels mounted to rotate in unisonabout a common axis, said cam wheels being in operative engagement withthe free ends of the valve stems in an arrangement such that eachsuccessive advance in rotation of the cam Wheels by a predeterminedangular amount reverses both the first and second valves to open one andclose the other, and rachet means responsive to each successiveactuation thereof to advance the cam wheels angularly by saidpredetermined amount.

A very important feature of the invention resides in valving the flow ofvolatile treating agent to each injector at a position in very closeproximity to the injector, and having a reduced discharge orifice forthe injector such that relatively little vaporization of the volatiletreating agent will occur in the injector with the desirable result ofminimization of refrigeration effect that would otherwise cause anaccumulation of frozen and adhering earth about the injector.

Another important feature of the invention resides in the provision ofindividual valves for the individual inectors, each of such valves beingprovided with micrometer-type adjustments so as to equalize the flow ofthe injectors at any desired rate of discharge.

Another very im ortant feature of the invention resides in the provisionof control means remote form the injectors which will operate theindividual valves in unison These, and other objects, aspects, andfeatures of the invention will become apparent as the followingdescription of a preferred embodiment of the invention proceeds, suchdescription to be taken in conjunction with the accompanying drawings,wherein:

FIGURE 1 is a perspective view of apparatus according to the invention;

FIGURE 2 is an enlarged central sectional view of one. of the valveunits;

FIGURE 3 is an enlarged fragmentary detail view of one of the valvingelements and its associated valve seat, this view showing the valvingelement in an open position.

FIGURE 4 is a view similar to FIGURE 3, but showing the valving elementin valve closing position;

FIGURE 5 is an enlarged central sectional view of the control meansprovided to actuate the plurality of in lividual valves such as the oneshown in FIGURE 2, this figure showing the structure in such conditionas to cause opening of all the individual valves;

FIGURE 6 is a fragmentary sectional view genera ly similar to FIGURE 5;however, this view showing the structure in such a condition as to causeall the individual valves to close;

FIGURE 7 is a broken view partially in section and with certain hiddendetails of structure shown in dashed outline of the means for operatingthe control structure shown in FIGURES 5 and 6;

FIGURE 8 is an elevational view of a filter provided in the maindistribution line;

FIGURE 9 is a central sectional view of the structure shown in FIGURE 8;

FIGURE 10 isan enlarged detail sectional view of one of the injectorunits taken upon the plane of the section line 18-10 in FIGURE 11; and,

FIGURE 11 is a broken diagrammatic view of the system of the presentinvention.

Referring now to the accompanying drawings wherein like numeralsdesignate like parts throughout the various views, the reference numeral10 designates generally app'ar-a'tus according to the present invention,such agricultural apparatus 10 comprising a wheel mounted vehicularframe 12 provided with a tow tongue 14 by means of which the apparatus19 can be traversed over fields undergoing treatment. The vehicularframe 12 which is supported by ground wheels 16 and 18 has mountedthereon a vessel 20 suitable for containing under superatmosphericpressure a liquified volatile substance such as liquified ammonia 22(see FIGURE 11).

A pairof shutoff valves 24 and 26 are mounted upon the top of the vessel20 so as to communicate with the interior of the vessel 20, and thevalve 24 is provided with an'inlet pipe 27 projecting downwardly withinthe interior of the vessel 20 through a vapor space 28, the surface 30of the ammonia and downwardly through the liquified ammonia 22 to aposition 32 closely spaced to the bottom of the interior of the vessel20. The arrangement is such that liquid ammonia 22 will enter the lowerend 32 of the pipe or conduit 27 and be conducted to a conduit 34 whenthe valve 24 is open, it being understood t that the liquified ammonia22 will, by virtue of its volatility and high vapor pressure, generate asuperatmosphen ic pressure within the vessel 20 under temperatureconditions prevailing in the area of use of the apparatus 10. The valve24 is fully opened during use of the apparatus 10, and is preferablyclosed at such times as the apparatus 10 is not to be used.

The line or conduit 34 communicates with a further line or conduit 36via a filter 38 (described in greater detail subsequently), and the lineor conduit 36 communicates with the inlet of a pressure regulator 48,the latter having its outlet connected to a line or conduit 42. Thepressure regulator 40 can conveniently be such as that marketed byFisher Governor Company of Marshal Town, Iowa, as their model No. 95H.The pressure regulator 40 is preferably adjusted to produce a constantdischarge pressure within the outlet line or conduit 42 thereof that issubstantially in excess of the pressure that might result in appreciablevaporization of ammonia. For example, the pressure regulator 40 can beadjusted to regulate the pressure in the line 42 to be 35 pounds persquare inch gauge or greater.

The line or conduit 42 has its outlet end connected to a manifold 44which in turn is connected to the inlets of a plurality of conduits 46,48, and 52, it being understood that the manifold 44 simply affordscontinuous fluid communication between the conduit 42 and all theconduits 46 through 52, and enables some saving in the total amount ofconduit that would otherwise be necessary to connect all the conduits 46through 52 to the outlet of the pressure regulator 40. Actually suchsaving in conduit will ordinarily substantially exceed that which mightbe apparent on inspection of FIGURE 1, inasmuch a FIG- URE 1 shows onlyfour injector units, whereas the apparatus 10 will normally include asubstantially greater number of injector units, only four of such unitsbeing shown in the drawings as illustration of a greater number wouldserve no useful purpose and would tend to obscure the actual invention.

The injector units referred to in the preceding paragraph are designatedby the reference numerals 54, 56, 58 and 60, such units beingrespectively connected via valves 62, 64, 66 and 68 to the distributionlines or conduits 46, 48, 5t) and 52. As will be seen presently, thevalves 62, 64, 66 and 68 are actuated in unison by a combined pressureregulator and pressure fluid control system indicated generally at 7 0.

As will be explained in greater detail subsequently, it will suffice forthe present to understand that the injectors 54 through 66] each arecomprised of a combined earth penetrating blade and conduit and thatsuch injectors discharge from adjacent their lower ends ammonia at ratessubject to the control of the valves 62 through 68, respectively.

Inasmuch as each of the valves 62 through 68 is identical, a detaileddescription of one of such valves will suffice for all, and accordingly,attention is directed to FIG- URES 2, 3 and 4 wherein the valve 62 isillustrated in detail. The valve 62 comprises a valve body 74 having anenlarged bore 76 in one end thereof, and such cylindrical bore 76 is inaxial alignment with a smaller cylindrical opening 78 that terminates atits end remote from the inner end 80 of the bore 76 at an annular valveseat 82 defined at the juncture of the opening 78 with a yet smaller andaxially aligned opening 84.

The end of the valve body 74 remote from the outer end of the bore '76is provided with a cylindrical recess that is in axial alignment withthe bore 76, the opening '78, the valve seat 82 and the opening 74. Therecess 90 has communication with the opening v84 by means of an opening92 coaxial with the opening 84 and having a diameter intermediate thatof the opening 84 and the recess 90. The arrangement is such that ashoulder 94 is defined at the juncture of the recess 90 and the opening92, and a filter screen 95 is disposed within the recess 90 and seatedagainst such annular shoulder 94. An annular coupling member 96 isdisposed within the recess 90 and has sealing engagement with thelateral confines of the latter by means of an O-ring seal 98 provided inthe periphery of the annular coupling member 96. The coupling member 96is retained in the recess 90 in a position abutting the screen 95 bymeans of a conventional C- shaped retaining ring of resilient characterthat is removably received within an annular groove 110. The member 96is internally threaded as shown, and the conduit 46 has a threaded endthreadingly fitted into the an-' nular coupling member 96, as clearlyshown.

A piston 112 is slidingly and sealingly fitted within the bore 76, anO-ring seal 114 being provided about the periphery of the piston 112 toassure such seal. Fixed to and preferably integral with the piston 112is a valve stem 116 that is slidingly and sealingly extended through theopening 78 toward the annular valve seat 82 as shown, and in order toassure a fluid-tight seal between the valve stem 116 and the sides ofthe opening 78, an O-ring 118 is preferably provided about the valvestem 116, as shown. The end of the valve stem 116 remote from the piston112 constitutes a valving element comprised of an annular shoulder 120in which an O-ring seal 122 is seated within an annular groove 124provided therefor. As clearly shown in FIGURE 4, movement of the valvestem 116 to the left in the opening 78 serves to seat the O-ring 122against the annular valve seat 82 to positively prevent any flow offluid through the cylindrical opening 84. The valving element alsoincludes a reduced end portion 126 of circular transverse section thatis tapered in diameter from the valve stem 116 as indicated at 128.Preferably, such taper 128 progressively increases from the valve stem116; however, the taper 128 can be linear, if desired. In the preferredconstruction, the projection 126 has a diameter at its major endsubstantially equal to the internal diameter of the opening 32, and thusaugments the sealing effect obtained by the O-ring 122. A lateralopening 136 is provided which communicates between the opening 78 andthe exterior of the valve body 74, and such opening 136 is internallythreaded for threaded connection to a conduit 132, such conduit 132being connected to the injector 5 as shown in FIGURES 1 and 11.

From the foregoing, it will be seen that the openings 84 and 130together with a portion of the extent of the opening 78 constitutes anL-shaped passageway through the valve 62 and a path of communicationbetween the conduits 46 and 132 that is controlled by the valvingelement comprised of the sealing ring 122 and the tapered projection 126that projects into the opening 84. The arrangement is such that when thevalve stem 116 is in the position shown in FlGURE 4, the valve 62 isclosed so as to shut off entirely fluid communication between theconduits 46 and 132, with such fluid communication becoming increasedprogressively upon movement of the valve stem 116 to the right as viewedin FIGURES 3 and 4-. In other words, a very short or small degree ofmovement of the valve stem 116 to the right will permit for a givenpressure differential a very small flow of fluid between the conduits 46and 132, and for such given pres sure differential progressively movingthe valve Stern 1116 to the right will result in a progressivelyincreasing rate of flow as between the conduits 46 and 132. Thus, thedegree of valve opening or fluid communication between the conduits 46and 132 is a function of the extent to which the valve stem 116 and thepiston 112 are moved to the right as seen in FIGURES 2, 3 and 4.

Adjustable means is provided for positively limiting the extent to whichthe valve stem 116 and the piston 112 can be moved to the right, and foran appreciation of such means, attention is directed to FIGURE 2,wherein it will be seen that a circular plate 136 is received within theouter end of the bore 76, and it should be noted that while the plate136 fits fairly snugly within the bore 76 it is not necessary, and infact it is preferred that such contact not be fluid tight. The plate 136is se cured against outward movement from within the bore 76 by means ofa resilient C-shaped retaining spring 138 that is removably seatedwithin an annular groove 141 as shown. The plate 136 is provided with acentral integral boss 142 that extends outwardly from the confines ofthe bore 76, and the plate 136 and its integral boss 142 are providedwith an axially extending internally threaded opening 144 therethrough.A threaded stop member 146 is threaded through the opening 144 to project toward the piston '112 from the plate 136. The inner end 148 of thestop member 146 is disposed directly in the travel path of a centralboss 150 carried by the piston 112, the arrangement being such thatmovement of the valve stem 116 to the right as shown in FIGURE 2 ispositively limited to such a position in which the boss 150 of thepiston 112 abuts the inner end 148 of the stop member 146. Such limitingposition is of course adjustable by means of threading the stop member146 through the plate 136 towards and away from the piston 112. In orderto calibrate and precisely adjust the axial position of the stop member146, the outer end of the stop member 146 is enlarged to constitute aknurled turning knob 152, and the turning knob 152 is provided with asleeve or skirt 154 that extends toward the plate 136 and whichrotatably embraces the boss 142. The boss is provided with axiallyextending indicia 156, and the sleeve 154 is provided withcircum'terentially extending indicia 153 in an arrangement such that theextent of exposure of the axial indicia 156 by the sleeve 154 taken inconjunction with the relationship of the indicia 158 as to its angularposition with respect to the indicia 156 enables the position of thestop member 146 to be accurately indicated.

A coiled compression spring 169 is disposed within the bore 76 andbiased between the piston *112 and the plate 136 so as to resilientlyand yieldingly urge the valve stem 116 to the left as seen in FIGURES 2,3 and 4, whereby the valve 62 is normally fully closed.

Pressure responsive means is provided for opening the valve 62 to theextent that such opening is limited by the stop member 146, such meanscomprising the provision of passageways 176 and 172 in the valve body 74which communicate between an annular chamber 174 within the bore 76 andthe exterior of the valve body 62, such passageways and 172 beingrespectively coupled by threaded connection to conduits 176 and 178. Itwill be evident upon inspection of FIGURE 2 that whenever a pressure ofsufficient magnitude prevails within the conduits 176 and 178, suchpressure is communicated to the chamber 17-41 and therein acts upon thepiston 112 to move such piston and the valve stem 116 to the rightagainst the bias of the spring 161) until further movement is preventedby the stop member 1 16. It is to be noted that the pressure prevailingwithin the conduit 176 is communicated to the conduit 178 via thepassageway 179, the chamber 174, and the passageway 172. The importanceof the latter consideration resides in the fact that providing eachvalve with two passageways or ports communicating With the pistonchamber enables a plurality of valves to be connected in series to 'asource of fluid pressure with a plug provided in one of the ports of thelast valve of the series with the result of pressure applied from asingle conduit serving to actuate the pistons of all the valves inunison and therefore open all the valves at one time, and similarlyrelease of pressure from any one of such chambers results in venting thesystem and consequent closure in unison of all the valves by the actionof the springs therein. Such arrangement is exemplified in FIGURES 1 and11 wherein the conduit 176 constitutes a line by means of which pressureis applied or vented from the piston chambers of all the valves 62through 68, and such series connection of the valves is comprised of theconduit 178 connected between the valves 62 and 64, a conduit 180connected between the valves 64 and 66, and a conduit 182 connectedbetwezn the valves 66 and 68. Since valve 68 is the last in the seriesof valves, a plug 184 is provided to close one of the two portscommunicating with the piston chamber therein.

It will be apparent from the foregoing that under static conditions, thepressures prevailing within all the piston chambers 174- of all thevalves 62 through 68 'are identical or of the same value by virtue ofthe connecting conduits 178, 180 and 182, and such pressure is equal tothat prevailing within the conduit 176.

Means is provided for controlling the pressure prevailing within theconduit 176 and therefore additionally controlling whether the valves 62through 68 are open or closed. Such means comprises the previouslymentioned combined pressure regulator and control valve means 76. Thecombined pressure regulator and control valve means is illustrated indetail in FEGURES 5, 6 and 7, wherein the reference numeral 2%designates a valve body provided with passageways 2512 and 204 withvalve means controlling fluid communication between such passageways,such valve means comprising an annular valve seat 206 at the juncture ofsuch passageways and a valving element 2118 movable to cooperate withthe annular valve seat for regulating the degree of communicationbetween the passageways 202 and 204. Means responsive to the pressureprevailing within the passageway 204 in relation to ambient atmosphericpressure is provided for controlling movement of the valving element208, such latter means comprising the body 200 having a piston chamber210 therein in which is slidingly and sealing disposed a piston 212. Thepiston is provided with an integral valve stem 214 that is in turnconnected to the previously mentioned valving element 208. The valvestem 214 is sealingly slidable through an opening 216 in the body 208that communicates between the passageway 284 and the piston chamber 210.The passageway 284 includes a lateral branch 218 that communicates withthe piston chamber 210 on the side of the piston remote from the valvestem, 214, in an arrangement such that pressure in the passageway 204and its branch 218 is applied against the piston 212 so as to urge thepiston 212 and the valve stem 214 to the left and towards closingposition of the valving element 288. Such movement of the piston 214 byfluid pressure within the passageway 218 is yieldingly opposed by acoiled compression spring 226 as will be apparent on inspection ofFIGURE 5. The piston chamber 210 is vented to atmosphere by an opening222 at a position such that the net force exerted by fluid pressuresagainst the piston 212 is a function of the diameters of the piston 212and the valve stem 214, as will be appreciated. The strength of thespring 228 is such in relation to the geometry of the piston 212 and thevalve stem 214 that the valve element 208 will tend to close or seatagainst the valve seat 286 Whenever the pressure within the passageway284 exceeds a predetermined pressure, which can conveniently beapproximately 40 pounds per square inch pressure. The force exertedagainst the end of the valve stem 214 directly by pressure prevailingwithin the passageway 202 is relatively immaterial because of the smallarea of exposure, as will be appreci'ated.

In view of the foregoing, the pressure prevailing within the pasageway204 is substantially of a predetermined value, it being assumed thatpressure prevailing within a conduit 230 and coupled to the passageway282 is in excess of such predetermined value. The conduit 230 is in factas will be seen on inspection of FIGURES 1 and 11, connected to theshutofi valve 26 so as to be in communication with the pressurized vaporspace 28 in the upper portion of the interior of the vessel 28.

The regulated pressure of passageway 284 is communicated by a lateralpassageway 232 to a valve structure comprising an annular valve seat 234that is operatively associated with a valving element 236 carried by avalve stem 238. The valve stem 238 is slidingly and sealinglyreciprocable within a cylindrical chamber 240 and is movable from aposition such as to close (see FIGURE 6) the passageway 232 to aposition opening such passageway (see FIGURE to the interior of thechamber 240. The valve element 236 and the valve stem 238 are yieldinglyurged to the open position shown in FIG- URE 5 by a coiled compressionspring 242 disposed within the chamber 240.

The chamber 240 is in continuous communication with the previouslymentioned conduit 176 by means of a passageway 250. Thus, when the valvestem 238 is in the position shown thereof in FIGURE 5, regulated fluidpressure is admitted to the conduit 176 from the vapor space 28 at thetop of the vessel 28. The body 200 is provided with a second valvestructure which includes an annular valve seat 252 and a valving element254 carried at one end of a valve stem 256 sealingly reciprocable withina cylindrical chamber 258 in the valve body 200. The chamber 258 hasdirect communication, when the valve stem 256 is in the position shownthereof in FIGURE 6, with the interior of the conduit 176 by way of apassageway 260 that merges with the passageway 256 within the body 206.The chamber 258 is It) vented to atmosphere by way of an opening 262 asclearly shown in the drawings.

By means subsequently described, the two valve elements 236 and 254 arealternately caused to make valve closing engagement with theirrespective annular valve seats. Such alternate positions or conditionsof such valves are shown in FIGURES 5 and 6. When the valves are in theposition shown thereof in FIGURE 5, fluid pressure from the conduit 238,regulated as described, is introduced into the conduit 176, and thevalving element 254 in engagement with its associated valve seat 252prevents any loss of pressure within the conduit 176 to atmospherethrough the opening 262. On the other hand, when the positions orconditions of the valves are such as shown in FIGURE 6, the valvingelement 236 in engagement with its respective seat 234 prevents fluid inthe pasageway 232 from reaching the pasageway 250 and consequently fromreaching the conduit 176, but rather, the unseating of the valvingelement 254 from its associated valve seat 252 results in fluid pressurewithin the conduit 176 being vented to atmospheric pressure through theopening 262. The two valve structures associated with the valve stems238 and 256 are quite similar as will be evident upon inspection of thedrawings, wherein it will be noted that the chamber 258 is also providedwith a coiled compression spring 270 generally similar to the previouslydescribed spring 242 in an arrangement such as to yieldingly urgeopening of the valve controlled by the valve stem 256.

Accordingly, when the structure 70 is in the condition shown thereof inFIGURE 5, fluid pressure from the top of the interior of the vessel 20is applied to the valves 62 through 68 so as to open all such valves;however, when the condition of the structure of the control means 76 issuch as indicated in FIGURE 6, the pressure prevailing within theconduit 176 is vented to atmosphere with the result that all the valves62 through '68 are closed in unison.

Attention is now directed to the means provided for interconnecting thevalve stems 238 and 256 in such a manner that such valves are inalternate positions, that is, one valve is closed when the other isopen, and whereby the reversal of such conditions can be manuallybrought about.

The means for interconnecting the valve stems 238 and 256 for alternatevalve closure and also for manually reversing the condition of suchvalves comprises a shaft 288 on which are positioned a pair of camwheels 282 and 284 for rotation therewith. As will be seen onconsideration of FIGURE 7, the lobes of such cam wheels 282 and 284 arealternated or interdigitated in angular positions circumferentiallyabout the shaft 280, whereby when the shaft 280 is in an angularposition such that one of the lobes of the cam wheel 284 is inengagement with the valve stem 256 so as to move the valve stem 256 intoa position closing its associated valve, the valve stem 238 is in aposition intermediate lobes of the cam wheel 282 with the result thatthe spring 242 opens the valve associated with the valve stem 238, suchcondition being shown in FIGURE 5. Alternatively, as shown in FIGURE 6,when the shaft 280 is turned through an angular rotation of 45, a lobeof the cam wheel 282 engages the valve stem 238 so as to close the valveassociated therewith, and the valve stem 256 is at an angular positionintermediate lobes of the cam wheel 284 with the result being that thecompression spring 270 opens the valve associated with the valve stem256.

It will be noted that in order to minimize wear as between the valvestems 238 and 256 and the cam wheels 282 and 284 spring pressed balls286 and 288 are recessed within the exposed ends of the valve stems 238and 256, respectively. Such spring pressed 'balls also smooth the actionof movement of the Valve stems, allows for wear such as does occur, andquite importantly prevents the valving elements being seated with excessforce.

In view of the foregoing, sequential successive steps of rotating theshaft 28% by angular increments of 45 results in successively reversingthe condition of each valve with one of such valves being closed whenthe other is open. Rachet means is provided for manually effecting suchsuccessive increments of angular advance in toration of the shaft 280,such cans comprising a U-shaped frame 2% journaled upon the same axis asthe shaft 8t), it being noted that the opposite ends of the shaft 28%are journaled for rotation at 292 in a pair of spaced ears or brackets(see FIGURE 1). Fixed to the shaft 230 at a position intermediate thecam wheels 282 and 284 is a rachet wheel 2% having rachet teeth 2%thereon that are angularly spaced from each other by A spring pressedrachet tooth 390 is mounted. within an arm 392 fixed to the U-shapedframe 290, the arrangement being such that a coiled spring 304yicldingly urges the rachet tooth into engagement with the teeth 2% ofthe rachet 2%. As clearly shown in FIGURE 7, clockwise angular move mentof the arm 302. about the axis of the shaft 289 results in correspondingrotation of the rachet wheel 2% by virtue of the positive engagementbetween the rachet tooth 300 and one of the teeth 298; however,anticlockwise movement of the arm 302 does not result in rotation of therachet wheel 2% and the shaft 280 because the rachet tooth 306 thenrachets over the inclined rachet teeth 298. It will be appreciated thatthe shaft 280 unless positively forced into rotation tends to stay ineither of the positions shown in FIGURES 5 and 6 for the reason that theouter ends of the cam lobes are relatively flat as compared to suchcamming surface existing between the lobes, and consequently the valvestems in their radial pressure against the cam wheels tend to retain thecam wheels in their present position. A coiled tension spring 310 (seeFlGURE l) is attached in such a manner as to yieldingly urge the arm 302into an anticlockwise direction of rotation and thereby cause the rachettooth 3% to move into a position engaging an adjacent tooth 238, itbeing understood that the arm 302 is prevented by means not shown frommoving more than slightly in excess of 45 by the spring 316. With thearm 3G2 and the rachet tooth 3% thus engaged With the next successivetooth 298, the operator may upon pulling from a remote position upon arope or flexible tension element 316 cause by virtue of the attachmentof the rope 316 to the outer end of the arm 302 a clockwise movement ofthe arm 302. such as to result in the rachet tooth 300 forcibly turningthe shaft 28% through an angle of 45, and result in consequent reversalof the condition of the valves. After the operator has pulled upon therope 316 to the extent necessary to effect the 45 increment of rotation(it being understood that means not shown prevent the arm 30?. frombeing moved through a greater angle), the operator then releases thetension applied by him to the rope 216, whereupon the spring are movesthe arm 392 into a position engaging the rachet tooth 300 with the nextsuccessive tooth.

The filter 38 (see FEGURE 9) is comprised of a pair of conical members323 and 322 having their major ends in abutment and peripherally securedby means of threaded fasteners 324. A circular screen 326 is provided,and the same being disposed within the housing defined by the conicalmembers 320 and 322 tohave its peripheral edge, which is imbcdded in anannular sealing member 328 seated between the major ends of the conicalhousing members 329 and 322, the minor ends of the conical housingmembers 3% and 322 being threadingly coupled to the conduits or lines 34and 36 as shown in FIGURE 9. The arrangement is such that the threadedfasteners 324 can be removed and the housing members 329 and 322separated so that the filter screen 326 along with its sealing ring 328can be cleaned and/ or replaced, after Which the filter 38 isreassembled and coupled to the conduits 3d and 36.

As clearly shown in FIGURES l0 and ll with respect to the injector 54,which injector 54 is representative of and identical to the otherinjectors 56, 58 and 60, the same is comprised of a steel blade havingan uppermost substantially straight portion 35% and a forwardly curvedlower portion 352. As is conventional the forward edge 354- of theinjector blade or knife 54 is sharpened throughout the vertical extentthereof. Also, the injector 54 is fixedly mounted on the frame 12. insuch a manner that the upper straight portion 359 thereof is forwardlyand downwardly inclined when the injector is in its ground penetratingposition as shown in FIGURE 1. The injector 54 CllilftilS fromconventional injectors in that the same is provided with an openingthroughout its longitudinal extent immediately adjacent the rear edge356 thereof, such opening being indicated at 358 in FIGURE 10 and beingformed in the rear edge of the blade by the latter having initially beenforged so as to have been spread or split laterally along the length ofthe rear edge of the blade, and the spread edges then being bent backand forced together at the lateral extremities thereof and weldedtogether as at 3643 to seal the seam resulting from such sequentialforging and bending operations. Such mode of fabrication results in theformation of the opening 358. The entire lower end of the opening 358 isclosed and welded to be fluid-tight, and thereafter small orifices oropenings 362 are formed by drilling entirely through the lower end ofthe blade and the opening 358, with the result that the lateral openings362 from the opening 358 are jointly of substantially reduced crosssectional size as compared to the opening 35%. In the use of apparatus16, ammonia passed by the valve 62 introduced by the conduit 132 intothe opening 358 and such introduced ammonia passes to the lower end ofthe opening 35$ after which it is discharged laterally to both sides ofthe injector 52 through the small openings or orifices 362. Similarly,ammonia introduced to the valve 54 by the conduit 43 passes from thevalve 64 through a conduit 370 to the injector 56 to be dischargedthrough the relatively small orifices 3'72 at the lower rear end of theinjector se.

The use of apparatus 10 will now be readily understood. The tank lit isinitially charged with liquid ammonia 22 through a conventional fillingfitting, not shown, and the apparatus 10 is then pulled or towed throughthe field being treated with the injectors lowered into groundpenetrating position (in a conventional manner and by conventionalapparatus, not show, which is well known in the art), it beingunderstood that the valves 24 and 26 are open, and it also beingunderstood that the arm 392 is actuated by applying tension to the rope316 so as to place the structure of the control means in the conditionshown thereof in FIGURE 5. In such condition, all the valves 62 through68 are open and ammonia is injected into the ground at a position belowthe surface thereof. Upon the operator reaching a point such as it isnecessary to make a turnaround, he jerks upon the rope 316 which resultsin venting the conduit 176 to the atmosphere and consequent closure inunison of all the valves 62 through 68. By jerking upon the rope theoperator causes a very rapid reversal of the valves and prompt closureof the valves 52 through 68. The operator may then elevate the injectors54 through 60 from ground penetrating position by conventional means,not shown. As soon as the operator has completed his turnaround and hasreinserted or caused the injectors 54 through 60 to penetrate thesurface of the ground, he again jerks upon the rope 316 with the resultof all the valves 62 through 68 being promptly opened in unison and suchprocedure is carried on to completion of treatment of the field.

It is extremely important to note that all the valves 62 through 68 arepositioned in very close proximity to the injectors 54- through 69 withthe result of very little ammonia being trapped between the valves 62through 68 and the discharge orifices of the injectors when such valvesare closed and consequently Wasted to the atmosphere or in any eventlost to the soil in an uneconomic and undesired fashion. It is alsodeemed noteworthy that actuation of all the valves 62 through 68 isaccomplished through the use of pressurized ammonia vapor only, and thatsuch operation is not dependent upon any other separately providedsource of fluid power.

The use of the micrometer-like means for individually adjusting theextent that each individual valve of the valves 62 through 68 is openedcoupled with the fact that the degree of opening of such valve isadjustable with precision enables uniform rates of injection as betweenthe various injectors, and also this enables adjustment of injectionsuch as to vary the concentration of the treatment of the field, thatis, to control with a considerable degree of precision the number ofpounds of ammonia injected per acre of land. For example, sometimes itis desired to treat with as little as 30 pounds of ammonia per acre,whereas sometimes it is desired to treat with ten times thisconcentration. Then, too, the adjustment affords a means forcompensating for the speed with which the apparatus is to be traversedover a field. The richness of application is of course also a functionof the rate of advance of the vehicle and such rate of advance will bereasonably constant for a given field, towing vehicle, operator, and soforth; however, if such rate of ad- Vance is such as to be widelyvariable, it is contemplated that conventional means can be provided inthe conduit 42 whereby a metering of the rate of flow of ammonia iseffected in a manner dependent upon the rate of rotation of the groundsupport wheels 16 and 18, though this is not preferred as it is desiredthat the rate of discharge be based on the setting of the valves 62 and68 and under conditions such that substantially solely liquid ammoniapasses through such valves.

It is extremely important to note that each of the valves 62 through 68constitute the major impediment to the flow of ammonia throughout thepassage thereof from the pressure regulator 40 to the soil beingtreated. In other words the valves 62 through 68 constitute not onlyconstrictions but the greatest constrictions in the cross sectional flowarea of the stream of ammonia throughout its passage from the pressureregulator 40 through the conduits, the valves and the injectors(including the discharge orifices of the latter), whereby the rate offlow of ammonia is predominantly dependent upon the constriction orreduction of available flow area established in an adjustablem-anner bythe valves 62 through 68. The importance of the relatively reducedeffective cross sectional area of flow presented by the valve 62 residesnot only in the fact that such relationship enables adjustment of thevalve 62 to control fluid flow, but also in the fact that the ammoniacan be maintained under a pressure during its entire passage from thepressure regulator 40 to the valve 62 such as to be maintainedsubstantially entirely in a liquid state, it being evident that suchpassage involves by far the majority of the distance of travel of theammonia from the pressure regulator to the injectors.

.An extremely important advantage of minimizing evaporation of theammonia prior to discharge through the injector orifices resides in thefact that excessively cold temperatures of the injectors is avoided, itbeing appreciated that excessively cold temperatures of the injectorunits results in freezing of the moisture in the soil in immediatecontact with the injectors, and this in turn results in the building upof an adhering heavy layer or thick coating of frozen earth about theinjectors such as to makeit impossible to proceed.

Still another extremely important advantage resulting from keeping theammonia at least mostly in the liquid state prior todischarge andsubstantially entirely in the liquid state of the valve 62 is that asubstantial stability in mass flow rate is obtained. Introducing ammoniaas substantially solely a liquid and at a constant pressure into aconstrict-ion results in a much more stable mass rate offiow than if aliquid including slugs of vapor were so introduced. Indeed, the massflow rate is much more stable than if a vapor containing slugs orintermittent collections of liquid were introduced at a constantpressure.

A further advantage of maintaining the liquid phase insofar as ispractically possible not only through the valve 62 but also through theinjector 54 resides in the fact that such additional soil treatingsubstances which may be dissolved in the liquid ammonia will not dropout of solution on evaporation of the ammonia and therefore will nottend to clog the valve 62, the injector 54, etc.

Although the apparatus 10 is obviously susceptible to other modes ofoperation such as by setting the output pressure of the regulator 49 toa low value such that substantial evaporation occurs in the conduit 42(more or less in accordance with the proposals of others, it beingobserved that some of such other proposals even include the provision ofmeans to facilitate such operation), the preferred method of operatingapparatus 20 is to set the regulator 40 to about 40 pounds per squareinch gauge (at least 35 pound per square inch gauge) or more which willmaintain the ammonia in substantially solely a liquid state to andthrough the valves 62 through 68, with the pressure in injectors 54through 60 being in the range of about 4 to about 15 pounds per squareinch guage. It has been found that with such pressure in the injectorswill result, during the flow of ammonia therethrough, in only a smallpercentage of the ammonia evaporating while still within the injectors(such percentage ordinarily being substantially less than 10%), and inany event being so small in amount that the refrigeration effect ofevapora tion will not cause the adherence of frozen earth to theinjectors.

Though not preferred and not necessary in order to realize theadvantages previously discussed, the central concept of the method ofthis invention can be carried into practice in such a manner that noevaporation of ammonia occurs prior to discharge. For example, thedischarge orifices 362 would be of such small size that an excessiverate of flow of liquid ammonia therethrough even when the pressurewithin the opening 358 is substantially in excess of the saturationpressure of ammonia at the temperature of the injector 54, and with thepressure regulator 40 being such as to introduce liquid ammonia into theconduit 42 at a still much higher pressure (sufliciently higher that thecorresponding pressure drop across the valve 62 is greater than the:pressure within the injector) whereby the rate of flow is controllableby the valve 62; such much higher pressure of introduction of liquidammonia into the conduit 42 being effected if necessary by employing apressure regulator 40 of the pump type having a constant pressure ofdischarge, whereby the pressure of introduction into the conduit can beregulated at a constant value that can exceed the pressure within thevessel 20.

In this extreme method of practicing the invention, the liquid ammoniawould suffer a pressure drop (from the high level constant pressure) ofadjustable magnitude on being passed through the variable constrictionconstituted by the valve 62, such pressure drop being substantially less(even for relatively low flow rates) than such as would reduce thepressure to the saturation pressure for temperature conditionsprevailing about the injector 54, and thence the liquid ammonia under apressure above the saturation pressure thereof would be expelled throughthe discharge orifices 362 as a liquid.

As stated above, such extreme mode of practicing the invention is notessential in the actual practice of the invention in order to obtain theadvantages thereof to a very satisfactory degree. It is believed thatsuch extreme mode of practicing the invention, while perhaps seeming tobe quite a lot more desirable from the standpoint of theory or of aperfectionist as such would positively prohibit all evaporation ofammonia except: after discharge from the injectors, is not nearly assuperior as might be suspected over the described practical conditionsof operation wherein the ammonia is under a pressure of about 4 to about15 pounds per square inch gauge in the injector 52 for the reason thatunder the dynamic conditions of fluid flow through the injector resultsin less evaporation in the injector 54 than the pressure would seem toindicate to be likely. Undoubtedly, at least to some extent, suchvaporization as may occur within the injector tends to suppress furthervaporization in the cooling of remaining liquid and therefore reducingits saturation pressure. Such cooling or refrigeration as may occur inpractice of the present method does not produce such a cold temperatureas to cause (as often experienced in conventional methods wherein alarge amount of vaporization occurs) the freezing and adherence of soilto the injector. Such small degree of cooling effect coupled with theheat of friction generated by movement of the injector through the soilprevents or adequately suppresses such adherence.

Needless to say, the method and apparatus of this invention can beextended to treating soil with other liquidified, normally gaseoussubstances such as, for example, low molecular weight saturated andunsaturated hydrocarbons, such as butane and butene.

Both the method and the apparatus of this invention are subject tonumerous variations in detail without departing from the spirit of theinvention, and according ly, attention is directed to the appendedclaims in order to ascertain the actual scope of the invention.

I claim:

1. In agricultural aparatus of the type including a plurality of groundpenetrating injectors for subsurface injection of soil treating fluids,such injectors being connected by individual conduits to a common sourceof supply of soil treating fluids, with valve means being provided toshut ofl fluid communication between the injectors and the source ofsupply through said conduits; the improvement wherein said valve meanscomprises an individual shutoff valve in each of the individual conduitswith each of such valves being disposed in its respective conduit at aposition therealong substantially spaced from the common source andmeans including a single control for actuating all said valves inunison, whereby all fluid communication between the injectors and thesource as well as the portions of the conduits between the source andthe valves can be shut off, and wherein each of said valves is providedwith resilient means continuously and yieldingly urging the valve towarda closed position, and wherein said means for actuating all the valvesincludes each valve including pressure controlled means responsive tothe application of a superatmospheric pressure thereto to open the valvein opposition to the resilient means, a fluid conduit means operativelyconnected to all said pressure controlled means, and said controlincluding means for selectively communicating the fluid conduit meanswith a source of pressurized fluid and ambient atmosphere.

2. The combination of claim 1, wherein said common source of soiltreating fluids comprises a pressure vessel adapted to contain avolatile fluid such as have an absolute vapor pressure substantially inexcess of atmospheric pressure at 0 0., and said means for selectivelycommunicating the conduit means is operatively connected to said vessel,whereby the latter can constitute a source of pressurized fluid.

3. The combination of claim 1, wherein each of said valves includes anannular valve seat and a tapered valve element received in said valveseat, said element being movable from a valve closing position in whichit is within and seated against the valve seat to open progressively thecross sectional area of an annular fluid flow path about the valveelement and through the valve seat, and said valve including stop meansmovable and select1vely positionable along the travel path of the valveelement, whereby the extent to which said valve can be opened by saidpressure controlled means can be ad- 16 justably limited, and the ratesof fluid flow of all the injectors equalized.

4. The combination of claim 1, wherein each of said valves comprises avalve body having a generally L- shaped fluid passageway therethroughthat is partially defined by an annular valve seat, said passagewaybeing interposed in the conduit in which the valve is positioned, saidbody being provided with a cylindrical bore in axial alignment with thevalve seat and having an inner end spaced from the passageway, said bodyhaving a cylindrical opening therein in axial alignment with the boreand the valve seat and extending from the inner end of the bore to thepassageway, a piston slidable in the bore to define a sealed chamber inthe bore intermediate the inner end of the latter and the piston, avalve stem fixed to the piston to project toward the valve seat, saidvalve stem slidably and sealingly extending through said opening, saidvalve stem being provided with a valving element at its end remote fromthe piston, said valving element being sealingly engageable with thevalve seat to close the passageway on movement of the piston toward theinner end of the bore, said valving element including a tapered portionprojecting into the valve seat, said valving element and the valve seatbeing so constructed and arranged that the passageway is progressivelyopened as the valving element is moved from sealing engagement with thevalve seat on movement of the piston from the inner end of the bore,said means for actuating all the valves including a control fluidpassageway in the valve body communicating with the chamber whereby afluid pressure can be applied to move the piston from the inner end ofthe bore, a plate mounted on the body at the outer end of the bore, acompression spring in the bore biased between the plate and the pistonfor yieldingly urging the piston toward the inner end of the bore, saidplate having a threaded opening therethrough, and a stop memberthreadingly extending through the threaded opening and into the travelpath of the piston, whereby a fine adjustment can be made as to thelimit of movement of the piston from the inner end of the bore andequally fine adjustment obtained as to the maximum opening of theL-shaped passageway.

5. The combination of claim 4, including the provision of micrometercalibration means comprising said plate having an axially extendingportion bearing axial indicia, and said stop member being provided withcircumferential indicia operatively associated with the axial indicia,whereby the axial position of the stop means is indicated.

6. The combination of claim 4, wherein conduit means establishes fluidpressure communication between the control fluid passageways of all thevalves.

'7. The combination of claim 6, wherein said single control comprisesvalve means operatively connected to said conduit means for selectivelyestablishing fluid communication with ambient atmosphere and with asource of pressurized fluid, whereby such valve means can selectivelyadmit fluid pressure to all the chambers of the valves to open all thelatter in unison to extents preset by the stop members of the valves andto relieve fluid pressure in all the chambers of the valves to close allthe latter in unison.

8. The combination of claim 7, wherein said valve means comprises firstand second shutofl valves each operatively connected to said conduitmeans for continuous fluid communication therewith, said first valvebeing connected to a source of pressurized fluid whereby opening of thefirst valve admits fluid under pressure to the conduit means, saidsecond valve being in communication with ambient atmosphere wherebyopening of the second valve vents the conduit means to atmosphere, andmeans operatively interconnecting said first and second valves foralternate closure of said first and second valves.

9. The combination of claim 8, wherein said first and second valves eachincluding an actuating valve stem,

1 7 with said valve stems being parallel to each other and having freeends, said means for alternate closure of said valves comprising a pairof cam Wheels mounted to rotate in unison about a common axis, said camwheels being in operative engagement with the free ends of the valvestems in an arrangement such that each successive advance in rotation ofthe cam wheels by a predetermined angular amount reverses both the firstand second valves to open one and close the other, and rachet meansresponsive to each successive actuation thereof to advance the camwheels angularly by said predetermined amount.

References Cited UNITED STATES PATENTS 0 ROBERT E. BAGWTLL, PrimaryExaminer.

